In the preparation of radiopharmaceuticals strategies to remove by-products, such as excess precursors have to be established for successful (radio-) synthesis and subsequent safe administration of compounds of clinical interest. Such reactions often employ non-radioactive organic precursors in amounts that are in large excess relative to the amount of the radiolabeling agent used. Excess precursors must then be removed from the reaction mixture before the radiolabeled compound can be applied to a patient for diagnostic and/or therapeutic applications.
Strategies to remove by-products, such as excess precursors have to be established for successful (radio-) synthesis and subsequent safe administration of compounds of clinical interest. Such reactions often employ non-radioactive organic precursors in amounts that are in large excess relative to the amount of the radiolabeling agent used. Excess precursors must then be removed from the reaction mixture before the radiolabeled compound can be applied to a patient for diagnostic and/or therapeutic applications.
The purification of the radiolabeled compound is normally achieved via a solid phase extraction (SPE) or a high-pressure liquid-chromatography (HPLC). Considering the half-life of most clinically useful radioisotopes, it is desirable to complete the radiosynthesis and purification prior to administration to a patient as rapidly as possible. For example, the half-life of 18 F is 110 minutes and 18 F-labeled targeting substrates are therefore synthesized and purified within one hour of clinical use. Regarding these time restrictions an HPLC purification is often time-consuming and tedious. Moreover this technique requires specialized equipment and can not be part of a disposable synthesis kit for cassette-type modules. This demands a purification and equilibrium of the HPLC prior the next synthesis. However, the same condition of the HPLC, especially of the HPLC column can not be guaranteed for every production run. Consequently, the consistency of the process can not be ensured.
With regard to technical requests and time-consumption a SPE purification is much less demanding and the SPE cartridges can also be part of a disposable synthesis kit for cassette-type modules. Nevertheless the cartridges used for purification of the radiolabeled compounds normally contain solid phase material in the range from 20 mg to 2 g. With this amount the complete removal of all by-products is often tedious and in many cases even not achievable. In view of the above, it is readily apparent that there is a need in the art for purification strategies which offer a reproducible, rapid and efficient separation of unwanted species from the final radiolabeled compound.
The current invention solves this technical problem by applying a disposable container for purification instead of using a multi-run HPLC purification step.